Recently, in memory cards such as bank cards, credit cards, or optical data recording cards have been developed by using optical data recording medium as data recording medium. FIG. 16 shows an example of an optical data recording card. That is to say, a band-shaped area 202 parallel to the longitudinal direction of the card on a rectangular card board 201 is formed by an optical data recording medium. Within this band-shaped area 202, a plurality of tracks T perpendicular to the longitudinal direction of the card are arranged in parallel with each other in the longitudinal direction of the card. Further, information signals are recorded on each track T in the form of so-called pit pattern or array P so as to be optically readable as shown in FIG. 17. In FIG. 17, a single track T is formed with a synchronizing signal portion 203 and a data portion 204, on both the portions of which the signal and the data are optically recorded in the form of pits P corresponding to digital signals.
The information recorded on each track within the area 202 of the optical data recording card 200 is read by an optical reading apparatus having a basic structure as shown in FIG. 18. In FIG. 18, the optical recording card 200 is fed in the longitudinal direction (the direction of arrow A) being pinched by a capstan 206 driven by a feed motor 205 and a pinch roller 207. An illumination light emitted from a light source 211 is illuminated through a condenser lens 212 upon at least one track T arranged within the band-shaped area 202 of the card. The reflected light, that is, the track reading light is allowed to be incident upon an optical sensor 214 through an objective lens 213. In general, a light emitting diode is used for the light source 211, however, it is also possible to use a lamp. As the optical sensor 214, linearly-arranged plural sensor elements (photocells) such as line sensor of charge coupled device (CCD) are used. The images projected upon the sensor elements are read on the basis of electric scanning method. Signals (track reading signals) from the optical sensor 214 are sent to a sample hold circuit 222 through an amplifier 221. Signal levels of sensor elements are sampled and held by the sample hold circuit 222 and then sent to a binary circuit 224 made up of a level discriminator through a low pass filter 223. The binary circuit 224 outputs a digital signal corresponding to the pits P on the track T. This digital signal is sent to a clock regenerating circuit 225 and a data regenerating circuit 226. Clock signals from the clock regenerating circuit 225 are sent to a clock input terminal of the data regenerating circuit 226 and further outputted through an output terminal 227. The data signal from the data regenerating circuit 226 is outputted from an output terminal 228.
In the optical data recording card 200, although the reliability of the recorded data is generally high, there exists some cases where errors occur if dust sticks onto the card. Conventionally errors are detected by adding a CRC (Cyclic Redundance Check) code to data with one track as one block or by writing data doubly. In these methods, however, in case burst error occurs due to scratches in the direction parallel or perpendicular to the track, there exists no effect of correcting errors. This is because the card is subjected to occurrence of straight scratches in the longitudinal (perpendicular to tracks) or the lateral (parallel to tracks) direction when the card is inserted into a card case or a cummutation ticket case or when the card is inserted through a card inserting slot of the card reading apparatus. In case burst errors occur due to such straight scratches as described above, it is impossible to regenerate correct information data.
With these problems in mind, therefore, it is the primary object of the present invention to provide an apparatus for recording and/or reproducing optical cards by which it is possible to regenerate correct information data and to provide an optical data recording card having a strong error correcting capability even if burst errors occur due to straight scratches on the card.